From: Binbin Wu <binbin.wu@linux.intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Sashiko Bot <sashiko-bot@kernel.org>,
Yan Zhao <yan.y.zhao@intel.com>,
Ackerley Tng <ackerleytng@google.com>,
Haotian Jiang <jianghaotian.sunday@gmail.com>
Subject: Re: [PATCH v2 2/2] KVM: TDX: Fix a benign off-by-one bug on the end GPA for INIT_MEM_REGION
Date: Mon, 10 Aug 2026 17:23:56 +0800 [thread overview]
Message-ID: <14193ad6-8046-44cb-99f5-d357e1b03d2d@linux.intel.com> (raw)
In-Reply-To: <20260806170602.4112602-3-seanjc@google.com>
On 8/7/2026 1:06 AM, Sean Christopherson wrote:
> When verifying that the incoming GPA rage for INIT_MEM_REGION doesn't wrap,
> check the inclusive last GPA, not the exclusive last GPA. Super duper
> technically, it's ok if the very last GPA is -1ull. In practice, the flaw
> is benign as KVM x86 disallows memslots with GPAs that exceed MAXPHYADDR,
> i.e. INIT_MEM_REGION would fail with -EINVAL anyways due to the memslot
> check in kvm_gmem_populate().
>
> Opportunistically use check_add_overflow() instead of manually checking for
> wrap, mostly so that the inclusive math doesn't need to be copy+pasted in
> the "is private" check.
>
> Fixes: c846b451d3c5 ("KVM: TDX: Add an ioctl to create initial guest memory")
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
prev parent reply other threads:[~2026-08-10 9:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-06 17:06 [PATCH v2 0/2] KVM: TDX: INIT_MEM_REGION fixes Sean Christopherson
2026-08-06 17:06 ` [PATCH v2 1/2] KVM: TDX: Reject INIT_MEM_REGION if number of bytes would overflow a u64 Sean Christopherson
2026-08-10 6:27 ` Yan Zhao
2026-08-10 8:45 ` Binbin Wu
2026-08-06 17:06 ` [PATCH v2 2/2] KVM: TDX: Fix a benign off-by-one bug on the end GPA for INIT_MEM_REGION Sean Christopherson
2026-08-10 6:58 ` Yan Zhao
2026-08-10 9:23 ` Binbin Wu [this message]
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